<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>三栏布局</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        html,body,div{
            height: 100%;
        }
        .left{
            width: 200px;
            background: red;
            float: left;
        }
        .center{
            background: yellow;
            float: left;
            width: calc(100% - 400px);
        }
        .right{
            background: green;
            width: 200px;
            float: left;
        }
    </style>
</head>
<body>
    <div class="left">左边</div>
    <div class="center">中间</div>
    <div class="right">右边</div>
</body>
</html>